JP4496160B2 - Proton conductive inorganic material, electrolyte membrane, electrode, membrane electrode composite, and fuel cell - Google Patents

Description

  The present invention relates to a proton conductive inorganic material suitable for battery members such as a fuel cell electrode and a fuel cell electrolyte membrane, and an electrolyte membrane, an electrode, a membrane electrode assembly, and a fuel cell using the proton conductive inorganic material. It is about.

  Proton-conducting solid electrolytes are being actively researched for applications in electrochromic materials and sensors, particularly recently in high energy density fuel cells operating at low temperatures.

  In a fuel cell, a fuel electrode (also referred to as an anode) is provided on one surface of a proton conductive electrolyte membrane, and an oxidant electrode (also referred to as a cathode) is provided on the other surface. A fuel such as hydrogen or methanol is supplied to the fuel electrode. On the other hand, an oxidizing agent is supplied to the oxidizing agent electrode. The fuel is oxidized electrochemically at the anode, producing protons and electrons. Protons pass through the proton conducting electrolyte membrane and reach the cathode. At the cathode, water is generated by protons, an oxidant, and electrons from an external circuit. By these reactions, electric power is extracted from the fuel cell.

  As the proton conductive electrolyte membrane, a perfluorosulfonic acid-containing polymer membrane, which is an organic polymer ion exchange membrane, is known. Specifically, those having a sulfonic acid group as an ion exchange group based on a copolymer of tetrafluoroethylene and perfluorovinyl ether, for example, Nafion (registered trademark) manufactured by DuPont are known. When a perfluorosulfonic acid-containing polymer is used for the electrolyte membrane, moisture contained in the membrane is reduced by drying, resulting in a decrease in proton conductivity. For this reason, use in the vicinity of 100 ° C. at which high output can be obtained requires strict water management, and the system becomes extremely complicated. In addition, since the perfluorosulfonic acid-containing polymer has a sparse molecular structure because it has a cluster structure, an electrolyte membrane using this polymer has high permeability to organic liquid fuels such as methanol, and organic liquid fuels. Tends to cause a so-called crossover that reaches the cathode side. When the crossover occurs, the organic liquid fuel and the oxidant react directly, and thus energy cannot be output as electric power. Therefore, there arises a problem that a stable output cannot be obtained.

  As an inorganic solid acid-based ion exchange membrane, a sulfuric acid-supported metal oxide having solid superacidity (for example, Patent Document 1) is known. Specifically, sulfuric acid is supported on the oxide surface containing one or more elements selected from zirconium, titanium, iron, tin, silicon, aluminum, molybdenum and tungsten, and sulfuric acid is immobilized on the oxide surface by heat treatment. is there. The sulfuric acid-supported metal oxide exhibits proton conductivity due to the immobilized sulfate radical. However, in sulfuric acid-supported metal oxides, the sulfate radicals deviate from hydrolysis, resulting in a decrease in proton conductivity. For this reason, it is low in stability for use as a material for proton conductive electrolyte membranes in fuel cells that generate water during the power generation process, particularly fuel cells that use liquid fuel, and is not suitable for long-term stable power supply. is there.

  Patent Document 2 describes that a metal oxide hydrate having proton conductivity is used as the proton conductive substance. In this metal oxide hydrate, the structure shrinks when the hydrated water is removed by drying by power generation at a high temperature and the like. There is a problem that power generation performance cannot be obtained.

Patent Document 3 describes a fuel cell electrolyte membrane in which an inorganic ionic conductor is supported on an inorganic porous carrier and is further impregnated with an ionic liquid. Specifically, it is described that alumina particles are baked on a glass woven fabric as an inorganic porous carrier using a solution containing zirconia, and then titania particles are baked on the carrier with a solution containing aluminum and vanadium. Yes.
JP 2002-216537 A JP 2003-142124 A JP-T-2004-515351

  An object of the present invention is to provide a proton conductive inorganic material, an electrolyte membrane, an electrode, a membrane electrode composite, and a fuel cell that can obtain high output characteristics.

The proton conductive inorganic material according to the present invention includes oxide particles containing at least one element X selected from the group consisting of W, Mo, Cr, B and V;
It contains at least one element Y selected from the group consisting of Sn, Hf, Ge, Ga, In, Ce and Nb, and an oxide carrier on which the oxide particles are supported. To do.

Moreover, the proton conductive inorganic material according to the present invention includes oxide particles containing at least one element X selected from the group consisting of W, Mo, Cr, B, and V;
Containing at least one element M selected from the group consisting of Ti, Zr, Si and Al, and an oxide carrier on which the oxide particles are supported;
It is contained in at least one of the oxide particles and the oxide carrier, and contains an element Z composed of Y, Sc, La, Sm, Gd, Mg, Ca, Sr, or Ba .

The electrolyte membrane according to the present invention includes oxide particles containing at least one element X selected from the group consisting of W, Mo, Cr, B, and V, Sn, Hf, Ge, Ga, In, and Ce. And a proton-conducting inorganic material containing at least one element Y selected from the group consisting of Nb and an oxide carrier on which the oxide particles are supported,
And a polymer material.

The electrolyte membrane according to the present invention is composed of oxide particles containing at least one element X selected from the group consisting of W, Mo, Cr, B, and V, and Ti, Zr, Si, and Al. Containing at least one kind of element M selected from the group, the oxide support on which the oxide particles are supported, and contained in at least one of the oxide particles and the oxide support, Y, Sc, A proton conductive inorganic material containing an element Z composed of La, Sm, Gd, Mg, Ca, Sr or Ba ;
And a polymer material.

The electrode according to the present invention includes an oxide particle containing at least one element X selected from the group consisting of W, Mo, Cr, B and V, Sn, Hf, Ge, Ga, In, Ce and A proton-conducting inorganic material containing at least one element Y selected from the group consisting of Nb and containing an oxide carrier on which the oxide particles are supported;
A polymer material;
And a redox catalyst.

The electrode according to the present invention includes an oxide particle containing at least one element X selected from the group consisting of W, Mo, Cr, B and V, and a group consisting of Ti, Zr, Si and Al. Containing at least one kind of element M selected from: an oxide carrier on which the oxide particles are supported; and at least one of the oxide particles and the oxide carrier, Y, Sc, La A proton conductive inorganic material containing an element Z composed of Sm, Gd, Mg, Ca, Sr or Ba ;
A polymer material;
And a redox catalyst.

A membrane electrode assembly according to the present invention is a membrane electrode assembly comprising a fuel electrode, an oxidant electrode, and an electrolyte membrane disposed between the fuel electrode and the oxidant electrode,
At least one of the fuel electrode, the oxidant electrode, and the electrolyte membrane is an oxide particle containing at least one element X selected from the group consisting of W, Mo, Cr, B, and V; Proton conductivity containing at least one element Y selected from the group consisting of Sn, Hf, Ge, Ga, In, Ce and Nb, and an oxide carrier on which the oxide particles are supported An inorganic material is included.

Moreover, the membrane electrode assembly according to the present invention is a membrane electrode assembly comprising a fuel electrode, an oxidant electrode, and an electrolyte membrane disposed between the fuel electrode and the oxidant electrode,
At least one of the fuel electrode, the oxidant electrode, and the electrolyte membrane is an oxide particle containing at least one element X selected from the group consisting of W, Mo, Cr, B, and V; , Containing at least one element M selected from the group consisting of Ti, Zr, Si and Al, an oxide carrier on which the oxide particles are supported, and the oxide particles and the oxide carriers Proton-conducting inorganic material containing at least one and containing element Z composed of Y, Sc, La, Sm, Gd, Mg, Ca, Sr or Ba is characterized.

A fuel cell according to the present invention is a fuel cell comprising a fuel electrode, an oxidant electrode, and an electrolyte membrane disposed between the fuel electrode and the oxidant electrode,
At least one of the fuel electrode, the oxidant electrode, and the electrolyte membrane is an oxide particle containing at least one element X selected from the group consisting of W, Mo, Cr, B, and V; Proton conductivity containing at least one element Y selected from the group consisting of Sn, Hf, Ge, Ga, In, Ce and Nb, and an oxide carrier on which the oxide particles are supported An inorganic material is included.

The fuel cell according to the present invention is a fuel cell comprising a fuel electrode, an oxidant electrode, and an electrolyte membrane disposed between the fuel electrode and the oxidant electrode,
At least one of the fuel electrode, the oxidant electrode, and the electrolyte membrane is an oxide particle containing at least one element X selected from the group consisting of W, Mo, Cr, B, and V; , Containing at least one element M selected from the group consisting of Ti, Zr, Si and Al, an oxide carrier on which the oxide particles are supported, and the oxide particles and the oxide carriers Proton-conducting inorganic material containing at least one and containing element Z composed of Y, Sc, La, Sm, Gd, Mg, Ca, Sr or Ba is characterized.

  According to the present invention, it is possible to provide a proton conductive inorganic material, an electrolyte membrane, an electrode, a membrane electrode composite, and a fuel cell that can obtain high output characteristics.

  The fuel cells described in Patent Documents 1 and 2 described above have not only high output but also the following problems. A large amount of entrained water is required for the conduction of protons in the proton conducting electrolyte membrane, and sufficient water must be supplied to the electrolyte. Therefore, water management that requires a complicated system is indispensable for stable power supply. Further, in the case of a fuel cell using a liquid fuel such as methanol, the methanol crossover could not be sufficiently controlled, so that a stable output cannot be obtained.

  According to the proton conductive inorganic materials according to the first and second embodiments of the present invention, not only high output characteristics can be obtained in the fuel cell, but also water management is facilitated, and crossover of liquid fuel such as methanol is facilitated. Can be suppressed. In addition, the proton conductive inorganic materials according to the first and second embodiments have high stability at high temperatures from room temperature to around 150 ° C., and high ion conductivity in a wide temperature range from room temperature to around 150 ° C. Can be maintained.

(First embodiment)
The proton conductive inorganic material according to the first embodiment includes oxide particles containing at least one element X selected from the group consisting of W, Mo, Cr, B, and V, Sn, Hf, Ge And at least one element Y selected from the group consisting of Ga, In, Ce and Nb, and an oxide carrier on which the oxide particles are supported.

  Although the exact proton conduction mechanism in the proton conductive inorganic material according to the first embodiment has not yet been elucidated, the element X is added to the surface of an oxide carrier containing the element Y (hereinafter referred to as oxide carrier A). By supporting the contained oxide particles (hereinafter referred to as oxide particles B), Lewis acid points are generated in the structure of the oxide particles B, and the Lewis acid points are hydrated to generate Bronsted acid. It is thought that a proton conduction field is formed. In addition, when the proton conductive inorganic material has an amorphous structure, it is presumed that this also contributes to the promotion of Lewis acid point generation.

  In addition to the proton generation reaction by the Lewis acid point, the number of entrained water molecules necessary for proton transfer can be reduced, so high proton conductivity is obtained with a small amount of water molecules present on the surface of the proton conductive inorganic material. Therefore, a large amount of power generation can be obtained without strict water management during power generation. Therefore, by including this proton conductive inorganic material in at least one of the fuel electrode, the oxidant electrode, and the electrolyte membrane, the cell resistance of the fuel cell can be lowered, and the maximum power generation amount of the fuel cell is increased. be able to.

  Moreover, according to the electrolyte membrane containing this proton conductive inorganic material, it is possible to suppress permeation of liquid fuel such as methanol. In particular, when a polymer material is added to the electrolyte membrane in order to enhance the binding property between the proton conductive inorganic materials, the density of the proton conductive electrolyte membrane is further increased, so that the permeation of liquid fuel can be further suppressed. It is.

  By the way, although the solubility of the oxide particles B varies depending on the element and pH environment, the oxide particles B may have water solubility. Since the oxide particles B are supported on the oxide carrier A having low water solubility, the dissolution of the oxide particles B in water can be suppressed, and the stability of the proton conductive inorganic material to water and liquid fuel can be improved. Can be high. Further, it is possible to avoid contamination of other fuel cell materials and devices by ions generated from the eluted oxide particles B. Therefore, according to the inorganic material according to the first embodiment, high long-term reliability can be obtained in the fuel cell. Furthermore, the manufacturing cost of the battery can be suppressed by using an inexpensive oxide carrier A as a base material.

  Confirmation that oxide particles B are supported on oxide carrier A can be examined by the method described below. For example, in the X-ray diffraction method (XRD), a crystal lattice diffraction pattern specific to a substance can be obtained for a crystalline substance. By comparing the diffraction patterns before and after the support, the presence or absence of the crystalline support can be confirmed. Instead of X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) can be used. On the other hand, if the support is an amorphous substance, since it cannot be confirmed from the diffraction pattern, the presence of the amorphous support can be confirmed by composition analysis using an instrument such as atomic absorption analysis. For composition analysis, electron probe microanalysis (EPMA) or X-ray electron spectroscopy (XPS) can be used.

FIG. 3 shows an electron micrograph of a proton conductive inorganic material in which oxide particles A made of MoO ₃ particles are supported on an oxide carrier A made of TiO ₂ particles. As shown in FIG. 3, fine particles present on the surface of the oxide carrier A are oxide particles B. FIG. 4 shows an electron micrograph of unsupported TiO ₂ particles. From FIG. 4, it can be understood that the unsupported TiO ₂ particles have a smooth surface without fine particles on the surface. Thus, by comparing with the surface state of the unsupported oxide support, it is possible to confirm the presence or absence of the support on the oxide support surface.

The oxide carrier A can be synthesized from a gas phase method in which the gas containing the element Y is decomposed to produce an oxide, or a sol-gel method using a metal alkoxide containing the element Y as a raw material. Is not limited. Further, the oxide carrier A may be formed from a complex oxide containing a plurality of elements. Examples of the element Y oxide include SnO ₂ , HfO ₂ , GeO ₂ , Ga ₂ O ₃ , In ₂ O ₃ , CeO ₂ , and Nb ₂ O ₅ . In order to make the proton conductivity sufficiently high, it is desirable to use SnO ₂ . By the way, examples of the shape of the oxide carrier A include a particle shape, a fiber shape, a flat plate shape, a layer shape, and a porous shape, but are not limited thereto.

  The support of the oxide particles B on the surface of the oxide carrier A can be performed, for example, by the method described below. The oxide carrier A is dispersed in a solution in which the substance containing the element X is dissolved, the solvent in the solution is evaporated, and then the substance containing the element X on the surface of the oxide carrier A is converted into oxide particles B by heat treatment. Thus, loading is performed. Examples of the solution in which the substance containing the element X is dissolved include an aqueous chloride solution, an aqueous nitrate solution, an aqueous hydrate solution, an aqueous oxoacid salt, and an alcohol solution of a metal alkoxide. The carrying method is not limited to this. Further, the oxide particles B may be formed from a composite oxide containing a plurality of elements.

  The oxide particles B may be supported on at least a part of the surface of the oxide carrier A. For example, the oxide particles B are scattered on the surface of the oxide carrier A or cover the surface of the oxide carrier A. The case where it is a layered material is mentioned. Further, the crystallinity of the oxide particles B and the oxide carrier A is not limited, and both the oxide particles B and the oxide carrier A may be crystalline. Considering the promotion of Lewis acid point generation, the possibility of contributing to the improvement of acidity, the reduction of the manufacturing cost, and the ease of the manufacturing process, the oxide particles B and the oxide support A are both amorphous. Is desirable. Further, the oxide particles B may be crystalline and the oxide carrier A may be amorphous, but it is more desirable that the oxide particles B are amorphous and the oxide carrier A is crystalline.

  The proton conductive inorganic material is formed, for example, by supporting the oxide particles B on the surface of the oxide carrier A by firing. Depending on the firing temperature, sufficient acidity may not be obtained due to insufficient bonding strength. In addition, the constituent oxides may be scattered, the target composition may not be obtained, and proton conduction sites may decrease. Further, the firing causes a change in the crystal structure accompanying an increase in the crystallinity of the oxide, and stress is generated in the proton conductive inorganic material. Due to the stress generated in the proton conductive inorganic material, the bonding force between the oxide carrier A and the oxide particles B may be reduced and may be separated. Separation of the oxide carrier A and the oxide particles B causes a decrease in acidity and a decrease in proton conduction sites.

The proton conductive inorganic material, Y, Sc, La, Sm , Gd, Mg, Ca, that the Sr and the element Z consisting of one type that will be selected from the group consisting of Ba is contained as the third component desired. Thereby, the oxide C containing the element Z can be functioned as a structure stabilizer of the proton conductive inorganic material. Specific examples of the oxide C include Y ₂ O ₃ , Sc ₂ O ₃ , La ₂ O ₃ , Sm ₂ O ₃ , Gd ₂ O ₃ , MgO, CaO, SrO and BaO. The oxide C can be contained as at least one component of the oxide support A and the oxide particles B. From the viewpoint of obtaining high output in the fuel cell, the oxide C is contained as a component of the oxide support A. It is desirable to make it.

  The content of the element Z in the proton conductive inorganic material is desirably in the range of 0.01 to 40 mol% when the total molar amount of the element X, the element Y, and the element Z is 100 mol%. By setting the content to 0.01 mol% or more, the stability of the proton conductive inorganic material can be improved. By setting the content to 40 mol% or less, the solid superacidity of the proton conductive inorganic material can be maintained. A more preferable range of the content is 0.1 to 10 mol%.

The proton conductive inorganic material desirably exhibits a solid superacid. The degree of proton dissociation can be expressed as acid strength, the acid strength of solid acid is expressed as Hammett acidity function H ₀ , and in the case of sulfuric acid, H ₀ is −11.93. It is more preferable that the proton conductive inorganic material exhibits solid superacidity that satisfies H ₀ <−11.93. Further, by optimizing the synthesis method, the acidity function H ₀ can be increased to an acidity of −20.00. Therefore, the acid strength of the proton conductive inorganic material can be set in the range of −20.00 ≦ H ₀ <−11.93. The solid superacidity of the proton conductive inorganic material can be determined indirectly by measuring the solid superacidity of the membrane containing the proton conductive inorganic material, as will be described later in Examples.

As described above, since the surface of the proton conductive inorganic material becomes a proton conduction field, the specific surface area of the proton conductive inorganic material is preferably as large as possible. However, if it exceeds 2000 m ² / g, handling and uniform synthesis are possible. It becomes difficult to control. Moreover, when the specific surface area is less than 10 m ² / g, there is a possibility that sufficient proton conductivity cannot be obtained. Therefore, the specific surface area is preferably in the range of 10 to 2000 m ² / g.

  The ratio (X / Y) of the element X of the oxide particle B to the element Y of the oxide carrier A is preferably in the range of 0.0001-20. When the element ratio (X / Y) is less than 0.0001, the supported amount is small and the proton conduction field is small, so that the proton conductivity may be lowered. On the other hand, if the element ratio (X / Y) exceeds 20, the supported amount is large, and the proton conduction field is covered with the oxide particles B containing the element X, so that the proton conductivity may be lowered. There is. A more desirable range of the element ratio (X / Y) is 0.01-1.

  The proton conductive inorganic material according to the first embodiment can be obtained, for example, by supporting the precursor of the oxide particles B on the oxide carrier A and then performing a heat treatment in an oxidizing atmosphere such as the atmosphere. When the treatment temperature is lower than 200 ° C., a sufficient chemical bond is not formed between the oxide carrier A and the oxide particles B, and the proton conductivity of the resulting inorganic material may be lowered. On the other hand, when the treatment temperature is higher than 1000 ° C., the particles are fused with each other and the specific surface area is reduced, so that high proton conductivity may not be obtained. The heat treatment temperature is preferably 200 to 1000 ° C. Further, at a low temperature of 200 ° C., a long heat treatment is required to form a bond between the oxide carrier A and the oxide particles B. On the other hand, since bonds are easily formed at a high temperature around 1000 ° C., synthesis by heat treatment in a short time is possible. Therefore, a more preferable range of the heat treatment temperature is 400 to 700 ° C.

(Second Embodiment)
The proton conductive inorganic material according to the second embodiment of the present invention includes oxide particles containing at least one element X selected from the group consisting of W, Mo, Cr, B and V (hereinafter referred to as oxidation). And an oxide carrier (hereinafter referred to as an oxide carrier) that contains at least one element M selected from the group consisting of Ti, Zr, Si, and Al and that supports the oxide particles. and referred to as M), wherein is contained in at least one of the oxide particles B and the oxide carrier M, one of Y, Sc, La, Sm, Gd, Mg, Ca, Ru is selected from the group consisting of Sr and Ba Containing element Z of various types.

  An oxide containing the element Z (hereinafter referred to as oxide C) can increase the structural stability of the proton-conductive inorganic material. As a result, when the oxide particles B are formed on the surface of the oxide carrier M by firing, it is possible to suppress the occurrence of stress on them, and thus the bond strength between the oxide carrier M and the oxide particles B is sufficiently high. Can be high. Further, scattering of constituent oxides during firing can be suppressed.

  As a result, the proton conductive inorganic material according to the second embodiment can generate a Lewis acid point in the structure of the oxide particle B by the interaction between the oxide carrier M and the oxide particle B. In addition, the proton conductive inorganic material according to the second embodiment can reduce the number of molecules of entrained water necessary for proton transmission.

  Therefore, by including this proton conductive inorganic material in at least one of the fuel electrode, the oxidant electrode, and the electrolyte membrane, the cell resistance of the fuel cell can be lowered, and the maximum power generation amount of the fuel cell is increased. be able to.

  Further, according to the electrolyte membrane containing the proton conductive inorganic material according to the second embodiment, it is possible to suppress the permeation of liquid fuel such as methanol. When a polymer material is added to the electrolyte membrane, the denseness of the electrolyte membrane is further increased, so that the permeation of liquid fuel can be further suppressed.

  It is desirable to use an oxide containing the element M as a support. Thereby, stability with respect to the water and liquid fuel of a proton conductive inorganic material can be made high. For this reason, it is possible to avoid contamination of other fuel cell materials and devices by ions generated by elution of the proton conductive inorganic material. Therefore, according to the inorganic material according to the second embodiment, high long-term reliability can be obtained in the fuel cell. Furthermore, the manufacturing cost of the battery can be suppressed by using an inexpensive oxide carrier M as a base material.

Specific examples of the oxide C can include the same types as described in the first embodiment. The oxide C can be contained as at least one component of the oxide carrier M and the oxide particles B. From the viewpoint of obtaining high output in the fuel cell, the oxide C is contained as a component of the oxide carrier M. It is desirable to make it.

  The content of the element Z in the proton conductive inorganic material is desirably in the range of 0.01 to 40 mol% when the total molar amount of the element X, the element M, and the element Z is 100 mol%. By setting the content to 0.01 mol% or more, the stability of the proton conductive inorganic material can be improved. By setting the content to 40 mol% or less, the solid superacidity of the proton conductive inorganic material can be maintained. A more preferable range of the content is 0.1 to 10 mol%.

  Confirmation that the oxide particles M are supported on the oxide carrier M can be performed by the same method as described in the first embodiment.

The oxide carrier M can be synthesized from a gas phase method of decomposing a gas containing the element M to produce an oxide, or a sol-gel method using a metal alkoxide containing the element M as a raw material. Is not limited. Further, the oxide carrier M may be formed from a complex oxide containing a plurality of elements. Examples of the oxide of element M include TiO ₂ , ZrO ₂ , SiO ₂ , Al ₂ O _{3 and the} like. In order to obtain high proton conductivity while suppressing the manufacturing cost, it is desirable to use TiO ₂ . By the way, examples of the shape of the oxide carrier M include particle shapes, fiber shapes, flat plate shapes, layer shapes, and porous shapes, but are not limited thereto.

  The oxide particles B are supported on the surface of the oxide carrier M by the same method as described in the first embodiment except that the oxide carrier M is used instead of the oxide carrier A. Can do.

  The oxide particles B may be supported on at least a part of the surface of the oxide carrier M. For example, the oxide particles B are scattered on the surface of the oxide carrier M or cover the surface of the oxide carrier M. The case where it is a layered material is mentioned. Further, the crystallinity of the oxide particles B and the oxide carrier M is not limited, and both the oxide particles B and the oxide carrier M may be crystalline. Considering the promotion of Lewis acid point generation, the possibility of contributing to the improvement of acidity, the reduction in production cost, and the ease of the production process, the oxide particles B and the oxide carrier M are both amorphous. Is desirable. Further, the oxide particles B may be crystalline and the oxide carrier M may be amorphous, but it is more desirable that the oxide particles B are amorphous and the oxide carrier M is crystalline.

The proton conductive inorganic material desirably exhibits a solid superacid. It is more preferable that the proton conductive inorganic material exhibits solid superacidity that satisfies H ₀ <−11.93. A more preferable range is −20.00 ≦ H ₀ <−11.93. The solid superacidity of the proton conductive inorganic material can be measured by the same method as described in the first embodiment.

The specific surface area of the proton conductive inorganic material according to the second embodiment is preferably in the range of 10 to 2000 m ² / g for the same reason as described in the first embodiment.

  The ratio (X / M) of the element X of the oxide particle B to the element M of the oxide carrier M is preferably in the range of 0.0001-20. By setting the element ratio (X / M) to 0.0001 or more, a sufficient carrying amount can be ensured. On the other hand, by setting the element ratio (X / M) to 20 or less, it is possible to prevent the proton conduction field from being covered with the oxide particles B containing the element X. A more desirable range of the element ratio (X / M) is 0.01-1.

  In the proton conductive inorganic material according to the second embodiment, for example, after a precursor of oxide particles B is supported on a carrier a composed of a composite oxide of an element Z and an element M, an oxidizing atmosphere as in the atmosphere is used. It can be obtained by heat treatment with. In order to form a sufficient chemical bond between the carrier a and the oxide particles B without fusing them, the heat treatment temperature is preferably 200 to 1000 ° C. A more preferable range of the heat treatment temperature is 400 to 700 ° C.

(Third embodiment)
The electrolyte membrane according to the third embodiment contains the proton conductive inorganic material according to the first embodiment or the proton conductive inorganic material according to the second embodiment, and a polymer material.

  In such an electrolyte membrane, it is more desirable that the proton conductive inorganic material is contained in the polymer material or the proton conductive inorganic material is bound by the polymer material.

  The polymer material is not particularly limited, and specific examples include polystyrene, polyether ketone, polyether ether ketone, polysulfone, polyether sulfone, and other engineering plastic materials. Further, the polymer material may be a material in which sulfonic acid, phosphoric acid or other proton carriers are doped, chemically bonded or immobilized, or a polymer material exhibiting proton conductivity such as perfluorosulfonic acid. Furthermore, it is possible to use a hydrophilic organic polymer containing at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an ether bond and an amide bond. Of these, hydrophilic organic polymers are desirable.

  By containing a hydrophilic organic polymer containing at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an ether bond and an amide bond in the electrolyte membrane, the proton conductive inorganic material and the hydrophilic organic polymer Phase separation can be suppressed, and dispersibility of the proton conductive inorganic material can be improved. Since the obtained electrolyte membrane has high water absorption, a sufficient amount of moisture can be supplied to the proton conductive inorganic material, high proton conductivity can be obtained, and membrane resistance can be reduced. Moreover, since this proton conductive membrane has high density, it is possible to suppress the permeation of liquid fuel and to suppress methanol crossover.

  Specific examples of the hydrophilic organic polymer will be given. Examples of the hydrophilic organic polymer having a hydroxyl group include polyvinyl alcohol. Examples of the hydrophilic organic polymer having a carboxyl group include polyacrylic acid. Examples of the organic polymer having an ether bond include polyethylene glycol and cellulose. Examples of the organic polymer having an amide bond include polyamide and polyvinyl pyrrolidone. An organic polymer having an ester bond is also conceivable.

  In particular, polyvinyl alcohol has high affinity with proton conductive inorganic materials, so that the dispersibility of proton conductive inorganic materials can be improved, and proton conductive inorganic materials and hydrophilic organic polymers And phase separation can be suppressed. As a result, an electrolyte membrane excellent in water absorption and methanol permeation suppression can be realized.

  The saponification degree of polyvinyl alcohol is desirably 50% or more and 100% or less. By setting the degree of saponification to 50% to 100%, the resistance of the electrolyte membrane can be reduced. The method for measuring the degree of saponification is as described below. Polyvinyl alcohol is completely saponified with sodium hydroxide. Whether it has been completely saponified can be confirmed by infrared absorption analysis. This can be determined by adding sulfuric acid to the saponified polymer solution and titrating excess sulfuric acid with sodium hydroxide to determine the unsaponified acetyl groups and the degree of saponification.

  The hydrophilic polymer desirably has an equilibrium moisture absorption rate of 5% or higher at 20 ° C. or higher. Since such a hydrophilic polymer has high water absorption, the membrane resistance of the electrolyte membrane can be further reduced. More preferred hydrophilic polymers are those having an equilibrium moisture absorption rate of 5% or more and 95% or less at 20 ° C. or higher and 90 ° C. or lower.

  The equilibrium moisture absorption rate was measured by measuring the weight of the sample film when the sample film was allowed to stand for one week in a constant temperature and humidity controlled at a temperature of 20 ° C. or higher and a relative humidity of 95% or higher. It measured from the difference with the weight after drying at 105 degreeC for 2 hours. Note that the sample film was prepared by dissolving a hydrophilic polymer in water and casting the obtained slurry.

  An electrolyte membrane using a hydrophilic organic polymer is produced, for example, by the method described below. A proton conductive inorganic material and a hydrophilic organic polymer are dispersed in a polar solvent such as water or alcohol to prepare a slurry. The slurry is cast on a glass substrate or a resin substrate and dried to remove the solvent, and then heat-treated at a temperature of 200 ° C. or lower. Although details are not clarified, the heat treatment at 200 ° C. or lower causes an oxidation reaction or a dehydration reaction between the proton conductive inorganic material and the hydrophilic organic polymer, an interaction consisting of a hydrogen bond, It is presumed that crystallization occurs and the hydrophilic organic polymer can be prevented from swelling and dissolving. At least with respect to polyvinyl alcohol, infrared spectroscopy (IR) shows that a hydrophilic hydroxyl group in polyvinyl alcohol is oxidized by a solid superacid to become a hydrophobic ketone group by heat treatment at a temperature of 200 ° C. or less. ) Result.

  When an electrolyte membrane is prepared by performing slurry preparation and heat treatment by the above-described method using polyvinyl alcohol, the solubility of polyvinyl alcohol in a polar solvent such as water is moderate without degrading the affinity for the proton conductive inorganic material. Therefore, the shape retention of the electrolyte membrane during water absorption can be improved while improving the dispersion stability of the slurry. Thereby, the electrolyte membrane excellent in water absorption and methanol permeation can be realized. In addition, by performing the above heat treatment, a film having excellent shape retention can be obtained even if water is used as a solvent used for slurry preparation. Therefore, the hydrophilicity of the film can be further increased by using water in the solvent. is there.

  It is necessary to carry out the heat treatment at a temperature at which the hydrophilic organic polymer is not decomposed or deteriorated, and it is desirable to perform the heat treatment at a temperature of 200 ° C. or lower. Moreover, in order to make the effect by heat treatment sufficient, the heat treatment temperature is desirably 100 ° C. or higher. A more preferable range of the heat treatment temperature is 130 ° C. or higher and 180 ° C. or lower.

  It is desirable that the mixing ratio between the proton conductive inorganic material and the polymer material satisfies the condition for preventing the permeation of liquid fuel while maintaining high proton conductivity. For this reason, it is desirable that the weight ratio (S / T) of the proton conductive inorganic material (S) to the total membrane weight (T) is in the range of 0.1 to 0.999. When the weight ratio (S / T) is smaller than 0.1, the continuity of the proton conductive inorganic material is lowered, and the conductivity may be lowered. A more preferable range of the weight ratio (S / T) is 0.5 to 0.999.

  When the electrolyte membrane is used as a solid electrolyte membrane of a fuel cell, it is generally used as a sheet, but is not limited to this and can be formed into a cylindrical shape. That is, there is a method in which a dispersion mixture of a proton conductive inorganic material and the above polymer material is directly cast into a film. Alternatively, a method of impregnating the dispersion mixture into a porous core material, a woven fabric, a non-woven fabric or the like can also be employed.

  The thickness of the electrolyte membrane is not particularly limited, but is preferably 10 μm or more in order to obtain a membrane that can withstand practical use, such as strength, liquid fuel permeability, and proton conductivity. Moreover, 300 micrometers or less are preferable for reduction of film resistance. In particular, in order to reduce the internal resistance of the fuel cell, 10 to 100 μm is more preferable.

  A method for controlling the thickness of the electrolyte membrane is not particularly limited, and examples thereof include the following methods. When casting a dispersion mixture of proton-conductive inorganic material and polymer material directly into a film shape, the amount of the dispersion mixture to be cast or the cast area can be changed. The film thickness can also be reduced by pressing.

(Fourth embodiment)
The electrode according to the fourth embodiment of the present invention is a redox catalyst, the proton conductive inorganic material according to the first embodiment or the proton conductive inorganic material according to the second embodiment, and a binder. A catalyst layer containing a polymer material is provided. This electrode can be used as a fuel electrode or an oxidant electrode of a fuel cell, or can be used as both a fuel electrode and an oxidant electrode.

  Each of the fuel electrode and the oxidant electrode is made of a gas diffusible structure such as a porous body, and fuel gas, liquid fuel, or oxidant gas can flow therethrough. In order to promote the oxidation reaction of the fuel on the fuel electrode and the oxygen reduction reaction on the oxidant electrode, a redox catalyst is supported on a conductive support material such as carbon. Examples of the oxidation-reduction catalyst include metal catalysts such as platinum, gold, silver, palladium, iridium, rhodium, ruthenium, iron, cobalt, nickel, chromium, tungsten, molybdenum, manganese, and vanadium. The metal catalyst may be a single metal, or a binary alloy or a ternary alloy. In particular, platinum has a high catalytic activity and is used in many cases. Further, the support material supporting the oxidation-reduction catalyst is only required to have conductivity, and a carbon material is often used. Examples thereof include carbon black such as furnace black, channel black, and acetylene black, activated carbon, and graphite.

The method for supporting the oxidation-reduction catalyst on the carbon material is not particularly limited. For example, the method described below can be employed. It is possible to support the redox catalyst on the carbon material by dispersing the carbon material in a solution in which the substance containing the metal element serving as the catalyst is dissolved, evaporating the solvent in the solution, and then heat-treating in a reducing atmosphere. is there. Examples of the solution in which the substance containing the metal element is dissolved include an aqueous chloride solution, an aqueous nitrate solution, an aqueous hydrate solution, an aqueous oxoacid salt, and an alcohol solution of a metal alkoxide. The particle size of the metal serving as the catalyst can be 1 to 50 nm. The amount of catalytic metal in the electrode can be 0.01 to 10 mg / cm ² .

The proton conductive inorganic material in the catalyst layer of the fuel electrode and the oxidant electrode serves as a route for transporting protons to the electrolyte membrane, so that it is desirable that sufficient continuity is maintained. The proton conductive inorganic material may be used alone or supported on the carbon material. The amount of the proton conductive inorganic material in the electrode is preferably 0.01 to 50 mg / cm ² .

  As the polymer material serving as the binder, the same kind of material as described in the third embodiment can be used.

  If the weight ratio (P / C) of the polymer material (P) to the total weight (C) of the catalyst layer is larger than 0.5, the continuity of the proton conductive inorganic material and the redox catalyst is lowered, and the proton conductivity There is a risk that the conductivity is lowered. In order to form a catalyst layer structure that maintains porosity while maintaining high proton conductivity and conductivity, the weight ratio (P / C) is preferably in the range of 0.001 to 0.5.

  The electrode may be formed as a single catalyst layer, or the catalyst layer may be formed on another support as an electrode. The method for forming the electrode is not particularly limited. For example, a redox catalyst, proton conductive inorganic material and polymer material are mixed and dispersed in an organic solvent such as water or alcohol to form a slurry, and this slurry is applied onto a support, dried and fired to form a catalyst layer. By doing so, an electrode is obtained. The support is not particularly limited, and for example, an electrolyte membrane can be used as the support. In this case, a membrane electrode assembly in which catalyst layers are formed on both surfaces of the electrolyte membrane can be obtained. The support may be made of carbon paper, carbon felt or carbon cloth having gas permeability and conductivity.

(Fifth embodiment)
The membrane electrode assembly according to the fifth embodiment of the present invention includes a fuel electrode, an oxidant electrode, and an electrolyte membrane disposed between the fuel electrode and the oxidant electrode. At least one of the fuel electrode, the oxidizer electrode, and the electrolyte membrane contains the proton conductive inorganic material according to the first embodiment or the proton conductive inorganic material according to the second embodiment. Specifically, a membrane electrode assembly including the electrolyte membrane according to the third embodiment, and a membrane using the electrode according to the fourth embodiment as a fuel electrode, an oxidant electrode, or both a fuel electrode and an oxidant electrode An electrode assembly, a membrane electrode assembly that includes the electrolyte membrane according to the third embodiment, and uses the electrode according to the fourth embodiment as a fuel electrode, an oxidizer electrode, or both a fuel electrode and an oxidizer electrode Can be mentioned.

The joining of the electrolyte membrane and the electrode is performed using an apparatus that can be heated and pressurized. Generally, it is performed by a hot press machine. The press temperature in that case should just be more than the glass transition temperature of the polymeric material used as a binder for an electrode and an electrolyte membrane, and can be 100-400 degreeC. The pressing pressure depends on the hardness of the electrode used, but can be in the range of 5 to 200 kg / cm ² .

(Sixth embodiment)
The fuel cell according to the sixth embodiment includes the membrane electrode assembly according to the fifth embodiment.

  A fuel cell according to a sixth embodiment will be described with reference to the drawings. FIG. 1 is a sectional view schematically showing a fuel cell according to a sixth embodiment of the present invention.

  The liquid fuel cell stack 100 shown in FIG. 1 is formed by stacking a plurality of single cells. A fuel introduction path 1 is disposed on the side surface of the stack 100. Liquid fuel is supplied to the fuel introduction path 1 from a liquid fuel tank (not shown) through an introduction pipe (not shown). The liquid fuel preferably contains methanol. For example, an aqueous methanol solution or methanol can be used as the liquid fuel. Each cell includes a fuel electrode (also referred to as an anode) 2, an oxidant electrode (also referred to as a cathode) 3, and an electrolyte membrane 4 disposed between the fuel electrode 2 and the oxidant electrode 3. A composite body (electromotive unit) 5 is provided. It is desirable that the fuel electrode 2 and the oxidant electrode 3 are made of a conductive porous body so that fuel and oxidant gas can be circulated and electrons can pass therethrough.

  Each unit cell further includes a fuel vaporization unit 6 stacked on the fuel electrode 2, a fuel permeation unit 7 stacked on the fuel vaporization unit 6, and a cathode separator 8 stacked on the oxidant electrode 3. The fuel permeation unit 7 has a function of holding liquid fuel. This liquid fuel is supplied from the fuel introduction path 1. The fuel vaporization unit 6 serves to guide the vaporized component of the liquid fuel held in the fuel permeation unit 7 to the fuel electrode 2. An oxidant gas supply groove 9 for flowing an oxidant gas is provided as a continuous groove on the surface of the cathode separator 8 facing the oxidant electrode 3. The cathode separator 8 also plays a role of connecting the adjacent electromotive parts 5 in series.

  When the stack 100 is configured by stacking single cells as shown in FIG. 1, the separator 5, the fuel permeation unit 7, and the fuel vaporization unit 6 also serve as a current collector plate that conducts generated electrons. It is desirable to be formed of a conductive material such as a porous body containing carbon.

  As described above, the separator 8 in the unit cell of FIG. 1 also has a function as a channel through which the oxidant gas flows. In this way, the number of components can be reduced by using the component 8 having both functions of a separator and a channel (hereinafter referred to as a channel separator), thereby further reducing the size of the fuel cell. Is possible. Alternatively, a normal channel can be used in place of the separator 8.

  As a method of supplying liquid fuel from a fuel storage tank (not shown) to the liquid fuel introduction path 1, there is a method in which the liquid fuel stored in the fuel storage tank is freely dropped and introduced into the liquid fuel introduction path 1. Can be mentioned. In this method, although there is a structural limitation that the fuel storage tank must be provided at a position higher than the upper surface of the stack 100, the liquid fuel can be reliably introduced into the liquid fuel introduction path 1. As another method, there is a method of drawing the liquid fuel from the fuel storage tank by the capillary force of the liquid fuel introduction unit 1. When this method is employed, the connection point between the fuel storage tank and the liquid fuel introduction path 1, that is, the position of the fuel inlet provided in the liquid fuel introduction path 1 does not need to be higher than the upper surface of the stack 100. Therefore, for example, when combined with the natural fall method, there is an advantage that the installation location of the fuel tank can be freely set.

  However, in order to continuously supply the liquid fuel introduced into the liquid fuel introduction path 1 by the capillary force to the fuel permeation unit 7 smoothly by the capillary force, the liquid fuel introduction path 1 is supplied to the fuel penetration part 7 by the capillary force of the liquid fuel introduction path 1. It is desirable to set the capillary force to be larger. The number of liquid fuel introduction paths 1 is not limited to one along the side surface of the stack 100, and the liquid fuel introduction paths 1 can be formed on the other side surface of the stack.

  The fuel storage tank as described above can be detachable from the battery body. Thus, by replacing the fuel storage tank, the operation of the battery can be continued for a long time. In addition, the liquid fuel is supplied from the fuel storage tank to the liquid fuel introduction path 1 in a configuration in which the liquid fuel is pushed out by the natural fall or the internal pressure in the tank as described above, or the capillary force of the liquid fuel introduction path 1. The fuel can be drawn out by the above.

  The liquid fuel introduced into the liquid fuel introduction path 1 by the method described above is supplied to the fuel permeation unit 7. The form of the fuel permeation unit 7 is not particularly limited as long as it has a function of holding the liquid fuel therein and supplying only the vaporized fuel to the fuel electrode 2 through the fuel vaporization unit 6. For example, a liquid fuel passage may be provided, and a gas-liquid separation membrane may be provided at the interface with the fuel vaporization unit 6. Furthermore, when liquid fuel is supplied to the fuel permeation unit 7 by capillary force without using an auxiliary device, the form of the fuel permeation unit 7 is particularly limited as long as the liquid fuel can be permeated by capillary force. In addition to porous materials made of particles and fillers, non-woven fabrics made by the papermaking method, woven fabrics made of fibers, etc., narrow gaps formed between plates made of glass or plastic are also used. be able to.

  Here, the case where a porous body is used as the fuel permeation portion 7 will be described. As the capillary force for drawing the liquid fuel to the fuel permeation unit 7 side, first, the capillary force of the porous body itself constituting the fuel permeation unit 7 is mentioned. When such capillary force is used, a so-called continuous hole is formed by connecting the holes of the fuel permeation unit 7 which is a porous body, and the diameter of the hole is controlled, and the side surface of the fuel permeation unit 7 on the liquid fuel introduction unit 1 side is controlled. By forming continuous holes from at least one other surface, it is possible to supply liquid fuel smoothly in the lateral direction with capillary force.

  The pore diameter and the like of the porous body used as the fuel permeation section 7 are not particularly limited as long as the liquid fuel in the liquid fuel introduction path 1 can be drawn in. The capillary of the liquid fuel introduction path 1 is not particularly limited. In consideration of the force, it is preferable to be about 0.01 to 150 μm. Moreover, it is preferable that the volume of the hole used as the parameter | index of the continuity of the hole in a porous body shall be about 20 to 90%. When the pore diameter is smaller than 0.01 μm, it is difficult to manufacture the fuel permeation portion 7. On the other hand, when it exceeds 150 μm, the capillary force may be reduced. Further, when the pore volume is less than 20%, the amount of continuous pores is reduced and the number of closed pores is increased, so that it is difficult to obtain sufficient capillary force. On the other hand, if the volume of the pores exceeds 90%, the amount of continuous pores increases, but the strength becomes weak and the manufacture becomes difficult. Practically, the porous body constituting the fuel permeation portion 7 preferably has a pore diameter in the range of 0.5 to 100 μm, and the pore volume is preferably in the range of 30 to 75%.

  Such a fuel cell is desirably operated at a temperature at which moisture management is easy in order to sufficiently display the proton conductivity of the electrolyte membrane. A preferable range of the operating temperature of the fuel cell is room temperature to 150 ° C. When operated at a high temperature of 50 ° C. to 150 ° C., the catalytic activity of the electrode is improved, so that the electrode overvoltage can be reduced.

  Hereinafter, the present invention will be described in more detail with reference to specific but non-limiting examples.

[Example 1]
A mixed solution in which 6 g of gallium oxide Ga ₂ O ₃ was added to 300 ml of ethanol solution in which 0.7 g of trimethyl borate B (OCH ₃ ) ₃ was dissolved was heated to 80 ° C. with constant stirring, and the evaporation rate was 100 ml / hour. To remove water. Thereafter, it was kept in a dryer at 100 ° C. for 12 hours to obtain a powder. After pulverizing this powder with an agate mortar to form a powder, it was heated in an alumina crucible to 700 ° C. at a rate of temperature increase of 100 ° C./hour, and further maintained at 700 ° C. for 4 hours. Boron oxide-supported gallium oxide was obtained. The element ratio (X / Y) of boron element (X) of boron oxide to gallium element (Y) of gallium oxide was 0.1. Further, the specific surface area of the proton conductive inorganic material was a value shown in Table 1 below. When X-ray diffraction measurement was performed on this boron oxide-supported gallium oxide, only diffraction peaks attributable to gallium oxide were observed, and it was confirmed that boron oxide had an amorphous structure. did it.

  In addition, the element ratio (X / Y) and specific surface area of proton conductive inorganic material powder were measured by the method demonstrated below.

  The element ratio (X / Y) was measured by dissolving the proton conductive inorganic material powder using acid or alkali, and determining the element ratio (X / Y) from this solution by atomic absorption analysis. The specific surface area was measured by the BET method.

  1 g of this proton conductive inorganic material powder was added to 2 g of an N, N-dimethylacetamide (DMAc) solution of 5% polyacrylonitrile (PAN) and stirred at room temperature for 10 minutes to prepare a slurry. This slurry was put into a petri dish made of a tetrafluoroethylene perfluoroalkoxy vinyl ether copolymer (PFA) resin, and the solvent was dried at 60 ° C. in the atmosphere to obtain an electrolyte membrane. The weight ratio S / T of the proton conductive inorganic material (S) to the total membrane weight (T) was 0.9, and the thickness of the electrolyte membrane was 151 μm.

[Example 2]
A mixed solution in which 6 g of gallium oxide Ga ₂ O ₃ was added to 300 ml of distilled water in which 1 g of vanadium chloride VCl ₃ was dissolved was heated to 80 ° C. with constant stirring, and water was removed at an evaporation rate of 100 ml / hour. Thereafter, it was kept in a dryer at 100 ° C. for 12 hours to obtain a powder. After pulverizing this powder with an agate mortar to form a powder, it was heated in an alumina crucible to 700 ° C. at a rate of temperature increase of 100 ° C./hour, and further maintained at 700 ° C. for 4 hours. A vanadium oxide-supported gallium oxide was obtained. The element ratio X / Y of vanadium element (X) of vanadium oxide to gallium element (Y) of gallium oxide was 0.1. The specific surface area of the proton conductive inorganic material was a value shown in Table 1 below. When X-ray diffraction measurement was performed on this vanadium oxide-supported gallium oxide, it was confirmed that all diffraction peaks were attributed to gallium oxide, and that vanadium oxide had an amorphous structure. did it.

  1 g of this proton conductive inorganic material powder was added to 2 g of an N, N-dimethylacetamide (DMAc) solution of 5% polyacrylonitrile (PAN) and stirred at room temperature for 10 minutes to prepare a slurry. This slurry was put into a petri dish made of a tetrafluoroethylene perfluoroalkoxy vinyl ether copolymer (PFA) resin, and the solvent was dried at 60 ° C. in the atmosphere to obtain an electrolyte membrane. The weight ratio S / T of the proton conductive inorganic material (S) to the total membrane weight (T) was 0.9, and the thickness of the electrolyte membrane was 150 μm.

Example 3
A mixed solution of 6 g of gallium oxide Ga ₂ O ₃ added to 300 ml of distilled water in which 1.7 g of chromium chloride hexahydrate CrCl ₃ · 6H ₂ O was dissolved was heated to 80 ° C. with constant stirring, and evaporated at 100 ml / hour. Water was removed at a rate. Thereafter, it was kept in a dryer at 100 ° C. for 12 hours to obtain a powder. After pulverizing this powder with an agate mortar to form a powder, it was heated in an alumina crucible to 700 ° C. at a rate of temperature increase of 100 ° C./hour, and further maintained at 700 ° C. for 4 hours. A chromium oxide-supported gallium oxide was obtained. The element ratio X / Y of chromium element (X) of chromium oxide to gallium element (Y) of gallium oxide was 0.1. The specific surface area of the proton conductive inorganic material was a value shown in Table 1 below. When X-ray diffraction measurement was performed on this chromium oxide-supported gallium oxide, it was confirmed that all diffraction peaks were attributed to gallium oxide, and that chromium oxide had an amorphous structure. did it.

  1 g of this proton conductive inorganic material powder was added to 2 g of DMAc solution of 5% PAN, and stirred at room temperature for 10 minutes to prepare a slurry. This slurry was placed in a petri dish made of PFA resin, and the solvent was dried at 60 ° C. in the atmosphere to obtain an electrolyte membrane. The ratio S / T of the proton conductive inorganic material (S) to the total membrane weight (T) was 0.9, and the thickness of the electrolyte membrane was 151 μm.

Example 4
A mixed solution in which 6 g of gallium oxide Ga ₂ O ₃ was added to 300 ml of distilled water in which 1.1 g of ammonium molybdate (NH ₄ ) ₆ Mo ₇ O ₂₄ · 4H ₂ O was dissolved was heated to 80 ° C. with constant stirring, and 100 ml Water was removed at an evaporation rate of / hour. Thereafter, it was kept in a dryer at 100 ° C. for 12 hours to obtain a powder. After pulverizing this powder with an agate mortar to form a powder, it was heated in an alumina crucible to 700 ° C. at a rate of temperature increase of 100 ° C./hour, and further maintained at 700 ° C. for 4 hours. A molybdenum oxide-supported gallium oxide was obtained. The element ratio X / Y of molybdenum element (X) of molybdenum oxide to gallium element (Y) of gallium oxide was 0.1. The specific surface area of the proton conductive inorganic material was a value shown in Table 1 below. When X-ray diffraction measurement was performed on this molybdenum oxide-supported gallium oxide, only diffraction peaks attributed to gallium oxide were observed, and it was confirmed that molybdenum oxide had an amorphous structure. did it.

  1 g of this proton conductive inorganic material powder was added to 2 g of DMAc solution of 5% PAN, and stirred at room temperature for 10 minutes to prepare a slurry. This slurry was placed in a petri dish made of PFA resin, and the solvent was dried at 60 ° C. in the atmosphere to obtain an electrolyte membrane. The ratio S / T of the proton conductive inorganic material (S) to the total membrane weight (T) was 0.9, and the thickness of the electrolyte membrane was 152 μm.

Example 5
A mixed solution obtained by adding 6 g of gallium oxide Ga ₂ O ₃ to 300 ml of ethanol solution in which 2.5 g of tungsten chloride WCl ₆ was dissolved was heated to 80 ° C. with constant stirring, and water was removed at an evaporation rate of 100 ml / hour. Thereafter, it was kept in a dryer at 100 ° C. for 12 hours to obtain a powder. After pulverizing this powder with an agate mortar to form a powder, it was heated in an alumina crucible to 700 ° C. at a rate of temperature increase of 100 ° C./hour, and further maintained at 700 ° C. for 4 hours. A tungsten oxide-supported gallium oxide was obtained. The element ratio X / Y of tungsten element (X) of tungsten oxide to gallium element (Y) of gallium oxide was 0.1. The specific surface area of the proton conductive inorganic material was a value shown in Table 1 below. When X-ray diffraction measurement was performed on this tungsten oxide-supported gallium oxide, all diffraction peaks attributed to gallium oxide were observed, and it was confirmed that tungsten oxide had an amorphous structure. did it.

  1 g of this proton conductive inorganic material powder was added to 2 g of DMAc solution of 5% PAN, and stirred at room temperature for 10 minutes to prepare a slurry. This slurry was placed in a petri dish made of PFA resin, and the solvent was dried at 60 ° C. in the atmosphere to obtain an electrolyte membrane. The ratio S / T of the proton conductive inorganic material (S) to the total membrane weight (T) was 0.9, and the thickness of the electrolyte membrane was 152 μm.

Example 6
Except for changing 6 g of gallium oxide to 9 g of indium oxide (In ₂ O ₃ ), the same operation as in Example 1 was performed to obtain boron oxide-supported indium oxide having an element ratio X / Y shown in Table 1 below. Using this boron oxide-supported indium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 153 μm was obtained.

Example 7
The same operation as in Example 2 was performed except that 6 g of gallium oxide was changed to 9 g of indium oxide (In ₂ O ₃ ) to obtain vanadium oxide-supported indium oxide having an element ratio X / Y shown in Table 1 below. Using this vanadium oxide-supported indium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm was obtained.

Example 8
The same operation as in Example 3 was performed except that 6 g of gallium oxide was changed to 9 g of indium oxide (In ₂ O ₃ ) to obtain chromium oxide-supported indium oxide having an element ratio X / Y shown in Table 1 below. Using this chromium oxide-supported indium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 153 μm was obtained.

Example 9
Except that 6 g of gallium oxide was changed to 9 g of indium oxide (In ₂ O ₃ ), the same operation as in Example 4 was performed to obtain molybdenum oxide-supported indium oxide having an element ratio X / Y shown in Table 1 below. Using this molybdenum oxide-supported indium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 151 μm was obtained.

Example 10
The same operation as in Example 5 was performed except that 6 g of gallium oxide was changed to 9 g of indium oxide (In ₂ O ₃ ) to obtain tungsten oxide-supported indium oxide having an element ratio X / Y shown in Table 1 below. Using this tungsten oxide-supported indium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 150 μm was obtained.

Example 11
Except that 6 g of gallium oxide was changed to 6.5 g of germanium oxide (GeO ₂ ), the same operation as in Example 1 was performed to obtain boron oxide-supported germanium oxide having an element ratio X / Y shown in Table 1 below. Using this boron oxide-supporting germanium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 149 μm was obtained.

Example 12
Except that 6 g of gallium oxide was changed to 6.5 g of germanium oxide (GeO ₂ ), the same operation as in Example 2 was performed to obtain vanadium oxide-supporting germanium oxide having an element ratio X / Y shown in Table 1 below. Using this vanadium oxide-supported germanium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 148 μm was obtained.

Example 13
The same operation as in Example 3 was performed except that 6 g of gallium oxide was changed to 6.5 g of germanium oxide (GeO ₂ ) to obtain chromium oxide-supporting germanium oxide having an element ratio X / Y shown in Table 1 below. Using this chromium oxide-supported germanium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 150 μm was obtained.

Example 14
Except that 6 g of gallium oxide was changed to 6.5 g of germanium oxide (GeO ₂ ), the same operation as in Example 4 was performed to obtain molybdenum oxide-supported germanium oxide having an element ratio X / Y shown in Table 1 below. Using this molybdenum oxide-supported germanium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm was obtained.

Example 15
Except that 6 g of gallium oxide was changed to 6.5 g of germanium oxide (GeO ₂ ), the same operation as in Example 5 was performed to obtain a tungsten oxide-supporting germanium oxide having an element ratio X / Y shown in Table 1 below. Using this tungsten oxide-supported germanium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 155 μm was obtained.

Example 16
Except that 6 g of gallium oxide was changed to 8 g of niobium oxide (Nb ₂ O ₅ ), the same operation as in Example 1 was performed to obtain boron oxide-supported niobium oxide having an element ratio X / Y shown in Table 1 below. Using this boron oxide-supported niobium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 150 μm was obtained.

Example 17
Except that 6 g of gallium oxide was changed to 8 g of niobium oxide (Nb ₂ O ₅ ), the same operation as in Example 2 was performed to obtain vanadium oxide-supported niobium oxide having an element ratio X / Y shown in Table 1 below. Using this vanadium oxide-supported niobium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 151 μm was obtained.

Example 18
The same operation as in Example 3 was carried out except that 6 g of gallium oxide was changed to 8 g of niobium oxide (Nb ₂ O ₅ ) to obtain chromium oxide-supported niobium oxide having an element ratio X / Y shown in Table 1 below. Using this chromium oxide-supported niobium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm was obtained.

Example 19
Except that 6 g of gallium oxide was changed to 8 g of niobium oxide (Nb ₂ O ₅ ), the same operation as in Example 4 was performed to obtain molybdenum oxide-supported niobium oxide having an element ratio X / Y shown in Table 1 below. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 154 μm was obtained.

Example 20
Except that 6 g of gallium oxide was changed to 8 g of niobium oxide (Nb ₂ O ₅ ), the same operation as in Example 5 was performed to obtain tungsten oxide-supported niobium oxide having an element ratio X / Y shown in Table 1 below. Using this tungsten oxide-supported niobium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 151 μm was obtained.

Example 21
Except that 6 g of gallium oxide was changed to 13 g of hafnium oxide (HfO ₂ ), the same operation as in Example 1 was performed to obtain boron oxide-supported hafnium oxide having an element ratio X / Y shown in Table 2 below. Using this boron oxide-supported hafnium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 153 μm was obtained.

[Example 22]
Except that 6 g of gallium oxide was changed to 13 g of hafnium oxide (HfO ₂ ), the same operation as in Example 2 was performed to obtain vanadium oxide-supported hafnium oxide having an element ratio X / Y shown in Table 2 below. Using this vanadium oxide-supported hafnium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm was obtained.

Example 23
Except that 6 g of gallium oxide was changed to 13 g of hafnium oxide (HfO ₂ ), the same operation as in Example 3 was performed to obtain chromium oxide-supported hafnium oxide having an element ratio X / Y shown in Table 2 below. Using this chromium oxide-supported hafnium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 150 μm was obtained.

Example 24
Except that 6 g of gallium oxide was changed to 13 g of hafnium oxide (HfO ₂ ), the same operation as in Example 4 was performed to obtain molybdenum oxide-supported hafnium oxide having an element ratio X / Y shown in Table 2 below. Using this molybdenum oxide-supported hafnium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 155 μm was obtained.

Example 25
Except that 6 g of gallium oxide was changed to 13 g of hafnium oxide (HfO ₂ ), the same operation as in Example 5 was performed to obtain tungsten oxide-supported hafnium oxide having an element ratio X / Y shown in Table 2 below. Using this tungsten oxide-supported hafnium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 150 μm was obtained.

Example 26
Except that 6 g of gallium oxide was changed to 11 g of cerium oxide (CeO ₂ ), the same operation as in Example 1 was performed to obtain boron oxide-supporting cerium oxide having an element ratio X / Y shown in Table 2 below. Using this boron oxide-supporting cerium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 153 μm was obtained.

Example 27
The same operation as in Example 2 was performed except that 6 g of gallium oxide was changed to 11 g of cerium oxide (CeO ₂ ), and vanadium oxide-supporting cerium oxide having an element ratio X / Y shown in Table 2 below was obtained. Using this vanadium oxide-supporting cerium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 151 μm was obtained.

Example 28
The same operation as in Example 3 was performed except that 6 g of gallium oxide was changed to 11 g of cerium oxide (CeO ₂ ) to obtain chromium oxide-supported cerium oxide having an element ratio X / Y shown in Table 2 below. Using this chromium oxide-supporting cerium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 154 μm was obtained.

Example 29
Except that 6 g of gallium oxide was changed to 11 g of cerium oxide (CeO ₂ ), the same operation as in Example 4 was performed to obtain molybdenum oxide-supported cerium oxide having an element ratio X / Y shown in Table 2 below. Using this cerium oxide carrying molybdenum oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm was obtained.

Example 30
Except that 6 g of gallium oxide was changed to 11 g of cerium oxide (CeO ₂ ), the same operation as in Example 5 was performed to obtain tungsten oxide-supporting cerium oxide having an element ratio X / Y shown in Table 2 below. Using this tungsten oxide-supporting cerium oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 150 μm was obtained.

Example 31
Except that 6 g of gallium oxide was changed to 9.5 g of tin oxide (SnO ₂ ), the same operation as in Example 1 was performed to obtain a boron oxide-supported tin oxide having an element ratio X / Y shown in Table 2 below. Using this boron oxide-supported tin oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm was obtained.

[Example 32]
The same operation as in Example 2 was carried out except that 6 g of gallium oxide was changed to 9.5 g of tin oxide (SnO ₂ ) to obtain vanadium oxide-supported tin oxide having an element ratio X / Y shown in Table 2 below. Using this vanadium oxide-supported tin oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 153 μm was obtained.

Example 33
The same operation as in Example 3 was performed except that 6 g of gallium oxide was changed to 9.5 g of tin oxide (SnO ₂ ) to obtain chromium oxide-supported tin oxide having an element ratio X / Y shown in Table 2 below. Using this chromium oxide-supported tin oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm was obtained.

Example 34
Except that 6 g of gallium oxide was changed to 9.5 g of tin oxide (SnO ₂ ), the same operation as in Example 4 was performed to obtain molybdenum oxide-supported tin oxide having an element ratio X / Y shown in Table 2 below. Using this molybdenum oxide-supported tin oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 153 μm was obtained.

Example 35
Except that 6 g of gallium oxide was changed to 9.5 g of tin oxide (SnO ₂ ), the same operation as in Example 5 was performed to obtain a tungsten oxide-supported tin oxide having an element ratio X / Y shown in Table 2 below. Using this tungsten oxide-supported tin oxide, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 151 μm was obtained.

Example 36
An electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 151 μm, except that the DMAc solution of 5% PAN was changed to a DMAc solution of 5% polybenzimidazole (PBI). Got.

Example 37
The same operation as in Example 17 was performed except that the DMAc solution of 5% PAN was changed to a toluene solution of 5% polystyrene (PS) to obtain an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm. It was.

[Comparative Example 1]
A Nafion 117 membrane manufactured by Dupont was prepared as an electrolyte membrane.

[Comparative Example 2]
Oxidation of tungsten oxide and silicon oxide in which ₂ g of tungsten oxide WO ₃ and 5 g of silicon oxide SiO ₂ are thoroughly mixed in an agate mortar and the element ratio of tungsten element (W) to silicon element (Si) is 0.1 A product mixture was obtained.

  1 g of this oxide mixture powder was added to 2 g of an N, N-dimethylacetamide (DMAc) solution of 5% polyacrylonitrile (PAN) and stirred at room temperature for 10 minutes to prepare a slurry. This slurry was put into a petri dish made of a tetrafluoroethylene perfluoroalkoxy vinyl ether copolymer (PFA) resin, and the solvent was dried at 60 ° C. in the atmosphere to obtain an electrolyte membrane. The weight ratio S / T was 0.9, and the thickness of the electrolyte membrane was 152 μm.

The obtained electrolyte membranes (proton conductive membranes) of Examples 1 to 37 were slightly swollen by applying moisture, and could be easily peeled off from the PFA resin petri dish. The membrane was flexible. Further, m-nitrotoluene (pKa = -11.99), p-nitrofluorobenzene (pKa = -12.40), p-nitrochlorobenzene (pKa = -12.70), m-nitrochlorobenzene (pKa = -13) .16) 2,4-dinitrotoluene (pKa = -13.75), 2,4-dinitrofluorobenzene (pKa = -14.52) 1,3,5-trinitrobenzene (pKa = -16.04) It was found that an acidic indicator consisting of Moreover, when the oxide superacid is colored, it is difficult to evaluate the solid acidity from the discoloration of the acid indicator. In such a case, the solid superacidity can also be measured using the ammonia temperature programmed desorption method (TPD) method. In this method, ammonia gas is adsorbed on a solid acid sample, and the desorption amount and desorption temperature of ammonia desorbed by raising the temperature of the sample are detected and analyzed. The Hammett acidity function H ₀ of each electrolyte membrane is shown in Tables 1 and 2 below.

  On the other hand, the electrolyte membranes of Comparative Examples 1 and 2 required a larger amount of water than in Examples 1 to 37 before swelling. Moreover, the electrolyte membranes of Comparative Examples 1 and 2 did not show solid superacidity.

  Moreover, the liquid fuel cell was assembled by the method demonstrated below using the electrolyte membrane (proton conductive membrane) of Examples 1-37 and Comparative Examples 1-2.

An oxidant electrode 3 was prepared by impregnating a 5% Nafion solution with an electrode containing a platinum-supported cathode catalyst (catalyst amount: 4 mg / cm ² Pt, manufactured by E-tek). In addition, an electrode containing a platinum / ruthenium-supported catalyst anode catalyst (catalyst amount: 4 mg / cm ² of Pt-Ru, manufactured by E-tek) impregnated with 5% Nafion solution was prepared as the fuel electrode 2.

An electrolyte membrane (proton conductive membrane) 4 is disposed between the fuel electrode 2 and the oxidant electrode 3 and bonded by hot pressing at 120 ° C. for 5 minutes at a pressure of 100 kg / cm ^2. And an electromotive part was obtained.

A carbon porous plate having an average pore diameter of 100 μm and a porosity of 70% as the fuel vaporization section 6 was laminated on the fuel electrode 2 of the electromotive section thus obtained. A carbon porous plate having an average pore diameter of 5 μm and a porosity of 40% as a fuel permeation unit 7 was disposed on the fuel vaporization unit 6. These were incorporated into the oxidant electrode holder 10 with the oxidant gas supply groove 9 and the fuel electrode holder 11 to produce a unit cell having the configuration shown in FIG. The reaction area of this unit cell is 10 cm ² . The oxidant gas supply groove 9 of the oxidant electrode holder 10 has a depth of 2 mm and a width of 1 mm.

Into the liquid fuel cell thus obtained, a 20% aqueous methanol solution was introduced as a liquid fuel from the side surface of the fuel permeation section 7 as shown in FIG. On the other hand, 1 atm of air as oxidant gas was allowed to flow through the gas channel 9 at 100 ml / min for power generation. Carbon dioxide gas (CO ₂ ) generated along with the power generation reaction was released from the fuel vaporization section 6 as shown in FIG. The maximum power generation is shown in Tables 1 and 2 below.

  Tables 1 and 2 show the measurement results of methanol permeability and membrane resistance for each electrolyte membrane (proton conductive membrane). Here, the methanol permeability and the membrane resistance were expressed as relative values, assuming that the Nafion 117 membrane of Comparative Example 1 was 1.

The methanol permeability is determined by inserting the electrolyte membrane into a cell with an area of 10 cm ² , putting 10% methanol aqueous solution in one cell and pure water in the other cell. The methanol concentration on the cell side containing water was measured by gas chromatography, and the methanol permeability was measured. The membrane was immersed in water for 16 hours to be ready for use as an electrolyte membrane, and then the water was drained and the methanol permeability was measured.

Moreover, the electrical resistance of the film was measured by a four-terminal DC method. That is, the electrolyte membrane was inserted into a cell having an area of 10 cm ² , 10% sulfuric acid aqueous solution was put into both cells, a direct current was applied at room temperature, the voltage drop due to the presence or absence of the electrolyte membrane was measured, and the conductivity was measured. .

  As is apparent from Tables 1 and 2, the electrolyte membranes of Examples 1 to 37 have a significantly lower methanol permeability than the electrolyte membranes of Comparative Examples 1 and 2, and the membrane resistance is that of the electrolyte membrane of Comparative Example 1. It can be seen that it is within the range of several times.

As shown in Comparative Example 1 of Table 1, in a fuel cell provided with a Nafion membrane 117 as an electrolyte membrane, a 20% methanol solution has too much crossover, so that only a maximum power generation amount of ² mW / cm ² is obtained. I couldn't. On the other hand, in the fuel cell provided with the electrolyte membranes of Examples 1 to 37 as the electrolyte membrane, a good power generation amount was obtained because the crossover was suppressed. Among them, the power generation amount of the fuel cells of Examples 31 to 35 using SnO ₂ as the oxide carrier was large and the most excellent was Example 35 in which tungsten oxide particles were supported.

  Further, as shown in Comparative Example 2 of Table 1, in a fuel cell including an electrolyte membrane using an oxide mixture in which tungsten oxide and silicon oxide are mixed as a proton conductor, the oxide has a proton conduction function. Since it was not expressed, membrane resistance was remarkably large, and almost no power generation was possible.

About the unit cell which used the proton-conductive membrane of Examples 1-37 as an electrolyte membrane, while supplying 20% methanol aqueous solution as a fuel, flowing air and heating both surfaces of a cell to 40 degreeC, 10 mA / cm < ² > The current was taken and the temporal stability of the battery performance was observed. As a result, the output was stable even after several hours. Furthermore, as a result of performing the same measurement at 150 ° C., the output was stable even after several hours.

For a fuel cell equipped with a Nafion 117 membrane (Comparative Example 1) as an electrolyte membrane, a 20% aqueous methanol solution was supplied as fuel, air was allowed to flow, and both sides of the cell were heated to 40 ° C. to produce a current of 10 mA / cm ² . Then, the temporal stability of the battery performance was observed. As a result, it became impossible to obtain an output within a few minutes. Furthermore, as a result of performing the same measurement at 150 ° C., the humidification could not be strictly controlled. Therefore, the electrolyte membrane was dried and an output could not be obtained.

Example 38
The same operation as in Example 4 was carried out except that 6 g of gallium oxide was changed to 7.8 g of magnesium oxide-added zirconia (11 mol% MgO-89 mol% ZrO ₂ ) and firing at 700 ° C. was changed to 850 ° C. A molybdenum oxide-supported magnesium oxide-added zirconia having an element ratio of 3 and a specific surface area of 51 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 153 μm was obtained.

  In addition, the element ratio (X / Y) in Table 3 means the ratio of the element X (for example, molybdenum) to the element Y (for example, zirconia). The element ratio (Z / X + Y + Z) is the molar amount of the element Z when the total molar amount of the element X, the element Y, and the element Z (for example, magnesium) is 100 mol%. An element ratio (Z / X + Y + Z) of 0.1 means that the molar amount of element Z is 10 mol%.

Example 39
The same operation as in Example 4 was carried out except that 6 g of gallium oxide was changed to 7.9 g of calcium oxide-added zirconia (11 mol% CaO-89 mol% ZrO ₂ ) and firing at 700 ° C. was changed to 850 ° C. A molybdenum oxide-supported calcium oxide-added zirconia having an element ratio of 3 and a specific surface area of 53 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 153 μm was obtained.

Example 40
The same operation as in Example 4 was performed except that 6 g of gallium oxide was changed to 8.3 g of strontium oxide-added zirconia (11 mol% SrO-89 mol% ZrO ₂ ), and baking at 700 ° C. was changed to 850 ° C. A molybdenum oxide-supported strontium oxide-added zirconia having the element ratio shown and a specific surface area of 52 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 151 μm was obtained.

Example 41
The same operation as in Example 4 was performed except that 6 g of gallium oxide was changed to 8.7 g of barium oxide-added zirconia (11 mol% BaO-89 mol% ZrO ₂ ) and calcination at 700 ° C. was changed to 850 ° C. A molybdenum oxide-supported barium oxide-added zirconia having the element ratio shown and a specific surface area of 55 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm was obtained.

Example 42
The same operation as in Example 4 was performed except that 6 g of gallium oxide was changed to 8.25 g of scandium oxide-added zirconia (8 mol% Sc ₂ O ₃ -92 mol% ZrO ₂ ), and the firing at 700 ° C. was changed to 850 ° C. A molybdenum oxide-supported scandium oxide-added zirconia having an element ratio shown in Table 3 and a specific surface area of 52 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 154 μm was obtained.

Example 43
The same operation as in Example 4 was carried out except that 6 g of gallium oxide was changed to 8.7 g of zirconia added with yttrium oxide (8 mol% Y ₂ O ₃ -92 mol% ZrO ₂ ) and calcination at 700 ° C. was changed to 850 ° C. A molybdenum oxide-supported yttrium oxide-added zirconia having an element ratio shown in Table 3 and a specific surface area of 53 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 151 μm was obtained.

Example 44
The same operation as in Example 4 was carried out except that 6 g of gallium oxide was changed to 9.25 g of lanthanum oxide-added zirconia (8 mol% La ₂ O ₃ -92 mol% ZrO ₂ ) and calcination at 700 ° C. was changed to 850 ° C. A molybdenum oxide-supported lanthanum oxide-added zirconia having an element ratio shown in Table 3 and a specific surface area of 51 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 153 μm was obtained.

Example 45
The same procedure as in Example 4 was performed except that 6 g of gallium oxide was changed to 13.5 g of samarium oxide-added ceria (10 mol% Sm ₂ O ₃ -90 mol% CeO ₂ ) and firing at 700 ° C. was changed to 850 ° C. A molybdenum oxide-supported samarium oxide-added ceria having an element ratio of 3 and a specific surface area of 52 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 152 μm was obtained.

Example 46
The same operation as in Example 4 was carried out except that 6 g of gallium oxide was changed to 13.6 g of gadolinium oxide-added ceria (10 mol% Gd ₂ O ₃ -90 mol% CeO ₂ ) and the baking at 700 ° C. was changed to 850 ° C. Molybdenum-supported gadolinium oxide-added ceria having an element ratio shown in Table 3 and a specific surface area of 54 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 154 μm was obtained.

[Comparative Example 3]
The same operation as in Example 4 was carried out except that 6 g of gallium oxide was changed to 7.5 g of zirconium oxide (ZrO ₂ ) and calcination at 700 ° C. was changed to 850 ° C., and the element ratios shown in Table 3 below were obtained. A molybdenum oxide supported zirconium having a surface area of 53 m ² / g was obtained. Using this, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 150 μm was obtained.

Using this electrolyte membrane, a liquid fuel cell was produced in the same manner as described in Example 1 above. For the obtained Examples 38 to 46 and Comparative Example 3, the maximum power generation amount of the fuel cell was measured, and the results are shown in Table 3 below.

  The electrolyte membranes of Examples 38 to 44 had lower resistance than the electrolyte membrane of Comparative Example 3, and the maximum power generation amount of the fuel cell was larger than that of Comparative Example 3. From this result, it was found that the output characteristics of the fuel cell were further improved by adding the element Z as the third component.

  In Comparative Example 3, the feed composition was adjusted so that the element ratio X / Y was 0.1, but molybdenum oxide sublimated from the support by firing at 850 ° C., and the element ratio X / Y was 0.08. It is considered that the proton conductive inorganic material obtained has a reduced proton conduction site, resulting in an increase in membrane resistance and a decrease in power generation. Although the cause is not clear, it is presumed that the bonding force between the support and the carrier was insufficient.

  On the other hand, in Examples 38 to 44 to which the third component was added, the target composition was obtained without the molybdenum oxide being scattered and detached from the carrier. This is presumably because the bonding force between the support and the carrier was sufficiently obtained. Addition of the basic oxide decreased the acidity of the proton conductive inorganic material, but the number of proton conductive sites increased, resulting in a decrease in membrane resistance and an increase in power generation.

  In addition, even when the type of element Y is changed to a type (Ce) different from those of Examples 38 to 44, the electrolyte membranes of Examples 45 to 46 to which element Z is added are examples in which element Z is not added. Compared to 29 electrolyte membranes, the maximum power generation of the fuel cell could be increased. From the above, it has been confirmed that the addition of the element Z improves the output characteristics of the fuel cell.

Example 47
A slurry was prepared by mixing the proton conductive inorganic material obtained in Example 1, platinum / ruthenium supported catalyst, PAN and DMAc in a weight ratio of 0.45 / 0.45 / 0.1 / 5.0. A fuel electrode having a catalyst amount of 4 mg / cm ² of Pt-Ru was prepared by coating on a carbon cloth of 32 mm × 32 mm.

In addition, a slurry was prepared by mixing the proton conductive inorganic material obtained in Example 1, the platinum-supported catalyst, PAN and DMAc at a weight ratio of 0.45 / 0.45 / 0.1 / 5.0. An oxidizer electrode having a catalyst amount of 4 mg / cm ² Pt was prepared by coating on a 32 mm × 32 mm carbon cloth.

  Furthermore, a Nafion 117 membrane similar to that used in Comparative Example 1 was prepared as the electrolyte membrane.

  A fuel cell was fabricated in the same manner as described in Example 1 except that the fuel electrode, the oxidant electrode, and the electrolyte membrane were used.

Example 48
A fuel cell was produced in the same manner as described in Example 1 except that the fuel electrode and oxidant electrode obtained in Example 47 and the electrolyte membrane obtained in Example 1 were used.

[Comparative Example 4]
The proton-conductive inorganic material obtained in Example 1 was supported with a platinum / ruthenium catalyst, and the catalyst-supported proton-conductive inorganic material, carbon, PAN and DMAc were combined at a weight ratio of 0.45 / 0.45 / 0.1. A slurry mixed at a ratio of /5.0 was prepared and applied onto a 32 mm × 32 mm carbon cloth to prepare a fuel electrode having a catalyst amount of 4 mg / cm ^{2 in} Pt-Ru.

Further, a platinum catalyst was supported on the proton conductive inorganic material obtained in Example 1, and the catalyst-supported proton conductive inorganic material, carbon, PAN and DMAc were combined at a weight ratio of 0.45 / 0.45 / 0.1. A slurry mixed at a ratio of /5.0 was prepared and applied onto a 32 mm × 32 mm carbon cloth to produce a catalytic amount of an oxidizer electrode having a Pt of 4 mg / cm ² .

  Furthermore, a Nafion 117 membrane similar to that used in Comparative Example 1 was prepared as the electrolyte membrane.

  A fuel cell was fabricated in the same manner as described in Example 1 except that the fuel electrode, the oxidant electrode, and the electrolyte membrane were used.

For the obtained Examples 47 and 48, the cell resistance and the maximum power generation amount of the fuel cell were measured, and the results are shown in Table 4 below. In Table 4, the results of Comparative Example 1 described above are also shown.

  As is apparent from Table 4, the membrane electrode composites obtained in Example 1 and Examples 47 and 48 exhibited higher output characteristics than the membrane electrode composite obtained in Comparative Example 1. This is because the proton conductor used in the electrode and electrolyte membrane of the example has a low resistance and a low cell resistance. Moreover, the output characteristics of Examples 1 and 48 are superior to Example 47 because the methanol permeability of the electrolyte membrane obtained in Example 1 is low as shown in Table 1.

  In Comparative Example 4, power generation of the fuel cell was attempted using a proton conductive inorganic material carrying a Pt—Ru catalyst or a Pt catalyst as an electrode, but only a very small amount of power could be obtained. It is considered that the catalyst supported on the proton conductive inorganic material was not able to obtain sufficient electrical conductivity and the electric resistance was high, so that power generation could not be performed.

Example 49
1 g of proton conductive inorganic material powder prepared in the same manner as described in Example 1 was added to 2 g of an aqueous solution of 5% polyvinyl alcohol (PVA), and stirred at room temperature for 10 minutes to prepare a slurry. This slurry was put into a petri dish made of a tetrafluoroethylene perfluoroalkoxy vinyl ether copolymer (PFA) resin, and the solvent was dried at 60 ° C. and 150 ° C. in steps in the air to obtain an electrolyte membrane. The weight ratio S / T was 0.9, and the thickness of the electrolyte membrane was 151 μm.

Example 50
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 2, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is An electrolyte membrane of 152 μm was obtained.

Example 51
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 3, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is An electrolyte membrane of 151 μm was obtained.

Example 52
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 4, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is An electrolyte membrane of 155 μm was obtained.

Example 53
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 5, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is An electrolyte membrane of 151 μm was obtained.

Example 54
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 6, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is An electrolyte membrane of 152 μm was obtained.

Example 55
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 7, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 153 μm. An electrolyte membrane was obtained.

Example 56
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 8, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 152 μm. An electrolyte membrane was obtained.

Example 57
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 9, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 152 μm. An electrolyte membrane was obtained.

Example 58
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 10, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 151 μm. An electrolyte membrane was obtained.

Example 59
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 11, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 152 μm. An electrolyte membrane was obtained.

Example 60
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 12, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 151 μm. An electrolyte membrane was obtained.

Example 61
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 13, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 150 μm. An electrolyte membrane was obtained.

Example 62
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 14, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 151 μm. An electrolyte membrane was obtained.

Example 63
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 15, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 153 μm. An electrolyte membrane was obtained.

[Example 64]
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 16, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 154 μm. An electrolyte membrane was obtained.

Example 65
Except for using the proton conductive inorganic material powder produced in the same manner as described in Example 17, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 152 μm. An electrolyte membrane was obtained.

Example 66
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 18, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 153 μm. An electrolyte membrane was obtained.

Example 67
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 19, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 154 μm. An electrolyte membrane was obtained.

Example 68
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 20, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 152 μm. An electrolyte membrane was obtained.

Example 69
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 21, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 151 μm. An electrolyte membrane was obtained.

Example 70
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 22, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 153 μm. An electrolyte membrane was obtained.

Example 71
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 23, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 152 μm. An electrolyte membrane was obtained.

Example 72
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 24, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 154 μm. An electrolyte membrane was obtained.

Example 73
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 25, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 152 μm. An electrolyte membrane was obtained.

Example 74
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 26, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 151 μm. An electrolyte membrane was obtained.

Example 75
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 27, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 153 μm. An electrolyte membrane was obtained.

Example 76
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 28, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 152 μm. An electrolyte membrane was obtained.

Example 77
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 29, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 151 μm. An electrolyte membrane was obtained.

Example 78
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 30, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 150 μm. An electrolyte membrane was obtained.

Example 79
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 31, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 154 μm. An electrolyte membrane was obtained.

Example 80
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 32, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 155 μm. An electrolyte membrane was obtained.

Example 81
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 33, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 153 μm. An electrolyte membrane was obtained.

Example 82
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 34, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 154 μm. An electrolyte membrane was obtained.

Example 83
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Example 35, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 151 μm. An electrolyte membrane was obtained.

Example 84
Proton conductive inorganic material powder prepared in the same manner as described in Example 17 was used, and 2 g of 5% PVA aqueous solution, 1.5 g of 5% PVA aqueous solution and 5% polyacrylic acid (PA) aqueous solution 0 were used. An electrolyte membrane having a weight ratio S / T of 0.9 and a thickness of 150 μm was obtained except that the mixed solution was changed to 2 g of 0.5 g.

Example 85
Example 49 and Example 49 except that the proton conductive inorganic material powder prepared in the same manner as described in Example 17 was used and 2 g of 5% PVA aqueous solution was changed to 2 g of 5% polyethylene glycol (PEG) aqueous solution. The same operation was performed to obtain an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 151 μm.

Example 86
The same operation as in Example 49 except that the proton conductive inorganic material powder prepared in the same manner as described in Example 17 was used and 2 g of 5% PVA aqueous solution was changed to 2 g of 5% Nylon 6 formic acid solution. As a result, an electrolyte membrane having a weight ratio S / T of 0.9 and a film thickness of 154 μm was obtained.

[Comparative Example 5]
Each powder of tungsten oxide WO ₃ 2 g and silicon oxide SiO ₂ 5 g was sufficiently mixed in an agate mortar to obtain an oxide mixture of tungsten oxide and silicon oxide in which the element ratio of tungsten element to silicon element was 0.1. .

  1 g of this oxide mixture powder was added to 2 g of 5% PVA aqueous solution and stirred at room temperature for 10 minutes to prepare a slurry. This slurry was put in a petri dish made of PFA resin, and the solvent was dried in the air at 60 ° C. and 150 ° C. in steps to obtain an electrolyte membrane. The weight ratio S / T was 0.9, and the thickness of the electrolyte membrane was 152 μm.

The obtained electrolyte membranes of Examples 49 to 86 were swollen greatly by applying moisture, and could be easily peeled off from the petri dish made of PFA resin. Moreover, the film | membrane of Examples 49-86 was equipped with the softness | flexibility. m-nitrotoluene (pKa = -11.99), p-nitrofluorobenzene (pKa = -12.40), p-nitrochlorobenzene (pKa = -12.70), m-nitrochlorobenzene (pKa = -13.16). ), 2,4-dinitrotoluene (pKa = -13.75), 2,4-dinitrofluorobenzene (pKa = -14.52) 1,3,5-trinitrobenzene (pKa = -16.04) It was found that the acid indicator showed solid superacidity. Moreover, when the oxide superacid is colored, it is difficult to evaluate the solid acidity from the discoloration of the acid indicator. In such a case, the solid superacidity can also be measured using the ammonia temperature programmed desorption method (TPD) method. The details of the ammonia temperature rising desorption method are as described above. The Hammett acidity function H ₀ of each electrolyte membrane is shown in Tables 5 to 6 below.

  On the other hand, the electrolyte membrane of Comparative Example 5 required a larger amount of moisture than in Examples 49 to 86 before swelling. Moreover, the electrolyte membrane of Comparative Example 5 did not show solid superacidity.

  Further, using the electrolyte membranes of Examples 49 to 86 and Comparative Example 5, a liquid fuel cell was assembled in the same manner as described in Example 1 above.

A 20% aqueous methanol solution was introduced into the liquid fuel cell from the side surface of the fuel permeation unit 7 by capillary force as shown in FIG. On the other hand, 1 atm of air as oxidant gas was allowed to flow through the gas channel 9 at 100 ml / min for power generation. Carbon dioxide gas (CO ₂ ) generated along with the power generation reaction was released from the fuel vaporization section 6 as shown in FIG. The maximum power generation is shown in Tables 5-6 below.

Tables 5 to 6 show the measurement results of methanol permeability and membrane resistance for each electrolyte membrane. Here, the methanol permeability and the membrane resistance were expressed as relative values, assuming that the Nafion 117 membrane of Comparative Example 1 was 1. The methanol permeability and membrane resistance were measured in the same manner as described in Example 1 above.

  As is apparent from Tables 5 to 6, it can be seen that the electrolyte membranes of Examples 49 to 86 have greatly reduced methanol permeability and membrane resistance as compared with the electrolyte membranes of Comparative Examples 1 and 5. Even when compared with Examples 1 to 37 described above, Examples 49 to 86 are superior. This is because the electrolyte membranes of Examples 49 to 86 use a hydrophilic organic polymer material containing at least one selected from the group consisting of hydroxyl group, carboxyl group, ether bond and amide bond. . Further, as shown in Example 65 and Examples 84 to 86, the wettability of the inorganic material and the organic material is changed by changing the polymer material used for the film to change the equilibrium moisture absorption rate of the polymer. It was found that the proton conductivity and methanol permeability were changed by changing the dispersibility of the membrane and the water absorption of the membrane, affecting the microstructure of the membrane. That is, by increasing the equilibrium moisture absorption rate to 10%, 20%, and 25%, the membrane resistance of the electrolyte membrane decreases, and the smaller the equilibrium moisture absorption rate, the smaller the methanol permeability.

As shown in Comparative Example 1 of Table 6, in a fuel cell equipped with a Nafion 117 membrane as an electrolyte membrane, a 20% methanol solution has large crossover and membrane resistance, and power generation of 2.0 mW / cm ² at the maximum. Only quantity could be obtained.

  Further, as shown in Comparative Example 5 in Table 6, in a fuel cell including an electrolyte membrane using an oxide mixture obtained by mixing tungsten oxide and silicon oxide as a proton conductor, the oxide has a proton conduction function. Since it was not expressed, membrane resistance was remarkably large, and almost no power generation was possible.

On the other hand, in the fuel cell provided with the proton conductive membranes of Examples 49 to 86 as the electrolyte membrane, a good power generation amount was obtained because the crossover was suppressed. The power generation amount of the fuel cells of Examples 79 to 83 using SnO ₂ as the oxide carrier was large and the most excellent was Example 83 in which tungsten oxide particles were supported.

About the unit cell which used the proton-conductive film | membrane of Examples 49-86 as an electrolyte membrane, while supplying 20% methanol aqueous solution as a fuel, flowing air and heating both surfaces of a cell to 40 degreeC, 10 mA / cm < ² > The current was taken and the temporal stability of the battery performance was observed. As a result, the output was stable even after several hours. Furthermore, as a result of performing the same measurement at 150 ° C., the output was stable even after several hours.

Example 87
A weight ratio S / T of 0.9 and a film thickness of 152 μm are the same as described in Example 49 except that a proton conductive inorganic material prepared in the same manner as described in Example 38 is used. An electrolyte membrane was obtained.

Example 88
A weight ratio S / T of 0.9 and a film thickness of 152 μm are the same as described in Example 49 except that a proton conductive inorganic material prepared in the same manner as described in Example 39 is used. An electrolyte membrane was obtained.

Example 89
A weight ratio S / T of 0.9 and a film thickness of 154 μm are the same as described in Example 49 except that a proton conductive inorganic material prepared in the same manner as described in Example 40 is used. An electrolyte membrane was obtained.

Example 90
A weight ratio S / T of 0.9 and a film thickness of 151 μm are the same as described in Example 49 except that a proton conductive inorganic material prepared in the same manner as described in Example 41 is used. An electrolyte membrane was obtained.

Example 91
A weight ratio S / T of 0.9 and a film thickness of 152 μm are the same as described in Example 49 except that a proton conductive inorganic material prepared in the same manner as described in Example 42 is used. An electrolyte membrane was obtained.

Example 92
A weight ratio S / T of 0.9 and a film thickness of 155 μm are the same as described in Example 49 except that a proton conductive inorganic material prepared in the same manner as described in Example 43 is used. An electrolyte membrane was obtained.

Example 93
A weight ratio S / T of 0.9 and a film thickness of 150 μm are the same as described in Example 49 except that a proton conductive inorganic material prepared in the same manner as described in Example 44 is used. An electrolyte membrane was obtained.

Example 94
A weight ratio S / T of 0.9 and a film thickness of 155 μm are the same as described in Example 49 except that a proton conductive inorganic material prepared in the same manner as described in Example 45 is used. An electrolyte membrane was obtained.

Example 95
A weight ratio S / T of 0.9 and a film thickness of 152 μm are the same as described in Example 49 except that a proton conductive inorganic material prepared in the same manner as described in Example 46 is used. An electrolyte membrane was obtained.

[Comparative Example 6]
Except for using the proton conductive inorganic material powder prepared in the same manner as described in Comparative Example 3, the same as described in Example 49, the weight ratio S / T is 0.9, and the film thickness is 151 μm. An electrolyte membrane was obtained.

A liquid fuel cell was produced in the same manner as described in Example 49 using the obtained electrolyte membrane. For the obtained Examples 87 to 95 and Comparative Example 6, the maximum power generation amount of the fuel cell was measured, and the results are shown in Table 7 below.

  The electrolyte membranes of Examples 87 to 93 had lower resistance than the electrolyte membrane of Comparative Example 6, and the maximum power generation amount of the fuel cell was larger than that of Comparative Example 6. From this result, it was found that the output characteristics of the fuel cell were further improved by adding the element Z as the third component.

  In Comparative Example 6, the feed composition was adjusted so that the element ratio X / Y was 0.1. However, molybdenum oxide sublimated from the support by firing at 850 ° C., and the element ratio X / Y was 0.08. The obtained proton conductive inorganic material is considered to have a high membrane resistance and reduced power generation due to a decrease in proton conduction sites. Although the cause is not clear, it is presumed that the bonding force between the support and the carrier was insufficient.

  On the other hand, in Examples 87 to 93 to which the third component was added, the target composition was obtained without the molybdenum oxide being scattered and detached from the carrier. This is presumably because the bonding force between the support and the carrier was sufficiently obtained. Addition of the basic oxide decreased the acidity of the proton conductive inorganic material, but the number of proton conductive sites increased, resulting in a decrease in membrane resistance and an increase in power generation.

  Even when the element Y is changed to a different type (Ce) from the examples 87 to 93, the electrolyte membranes of the examples 94 to 95 to which the element Z is added are the electrolyte membranes of the example 77 to which the element Z is not added. The maximum power generation of the fuel cell could be increased compared to From the above, it was confirmed that the output characteristics of the fuel cell were improved by adding the element Z.

Example 96
A slurry was prepared by mixing the proton conductive inorganic material obtained in Example 49, platinum / ruthenium supported catalyst, PVA and water in a weight ratio of 0.45 / 0.45 / 0.1 / 5.0. A catalyst electrode having a catalyst amount of 4 mg / cm ² of Pt-Ru was prepared by coating on a carbon cloth of 32 mm × 32 mm.

In addition, a slurry was prepared by mixing the proton conductive inorganic material obtained in Example 49, the platinum-supported catalyst, PVA and water at a weight ratio of 0.45 / 0.45 / 0.1 / 5.0. Then, it was coated on a 32 mm × 32 mm carbon cloth to produce a catalytic amount of an oxidizer electrode having a Pt of 4 mg / cm ² .

  Furthermore, a Nafion 117 membrane similar to that used in Comparative Example 1 was prepared as the electrolyte membrane.

  A fuel cell was fabricated in the same manner as described in Example 49, except that the fuel electrode, the oxidant electrode, and the electrolyte membrane were used.

Example 97
A fuel cell was fabricated in the same manner as described in Example 49 except that the fuel electrode and oxidant electrode obtained in Example 96 and the electrolyte membrane obtained in Example 49 were used.

[Comparative Example 7]
The proton-conductive inorganic material obtained in Example 49 was supported with a platinum / ruthenium catalyst, and the catalyst-supported proton-conductive inorganic material, carbon, PVA, and water in a weight ratio of 0.45 / 0.45 / 0.1. A slurry mixed at a ratio of /5.0 was prepared and applied onto a 32 mm × 32 mm carbon cloth to prepare a fuel electrode having a catalyst amount of 4 mg / cm ^{2 in} Pt-Ru.

In addition, a platinum catalyst was supported on the proton conductive inorganic material obtained in Example 49, and the catalyst-supported proton conductive inorganic material, carbon, PVA, and water in a weight ratio of 0.45 / 0.45 / 0.1. A slurry mixed at a ratio of /5.0 was prepared and applied onto a 32 mm × 32 mm carbon cloth to produce a catalytic amount of an oxidizer electrode having a Pt of 4 mg / cm ² .

  Furthermore, a Nafion 117 membrane similar to that used in Comparative Example 1 was prepared as the electrolyte membrane.

  A fuel cell was fabricated in the same manner as described in Example 49, except that the fuel electrode, the oxidant electrode, and the electrolyte membrane were used.

For the obtained Examples 96 and 97, the cell resistance and the maximum power generation amount of the fuel cell were measured, and the results are shown in Table 6 below. Table 6 shows the results of Example 49 and Comparative Example 1 described above.

  As is clear from Table 8, the membrane electrode composites obtained in Example 49 and Examples 96 and 97 showed higher output characteristics than the membrane electrode composite obtained in Comparative Example 1. This is because the proton conductor used in the electrode and electrolyte membrane of the example has a low resistance and a low cell resistance. Further, the output characteristics of Examples 49 and 97 are superior to Example 96 because the methanol permeability of the electrolyte membrane obtained in Example 49 is low as shown in Table 5.

  Further, in Comparative Example 7, power generation of the fuel cell was attempted using a proton conductive inorganic material carrying a Pt-Ru catalyst or a Pt catalyst as an electrode, but only a very small amount of power could be obtained. It is considered that the catalyst supported on the proton conductive inorganic material was not able to obtain sufficient electrical conductivity and the electric resistance was high, so that power generation could not be performed.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

Sectional drawing which showed typically the fuel cell which concerns on the 6th Embodiment of this invention. Sectional drawing which showed typically the another fuel cell which concerns on the 6th Embodiment of this invention. The electron micrograph of the proton-conductive inorganic material which concerns on the 1st Embodiment of this invention. An electron micrograph of TiO ₂ particles.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid fuel introduction path, 2 ... Anode, 3 ... Cathode, 4 ... Electrolyte membrane, 5 ... Membrane electrode assembly (electromotive part), 6 ... Fuel vaporization part, 7 ... Fuel penetration part, 8 ... Cathode separator, 9 ... oxidant gas supply groove, 10 ... oxidant electrode side holder, 11 ... fuel electrode side holder, 100 ... stack.

Claims (10)

Oxide particles containing at least one element X selected from the group consisting of W, Mo, Cr, B and V;
It contains at least one element Y selected from the group consisting of Sn, Hf, Ge, Ga, In, Ce and Nb, and an oxide carrier on which the oxide particles are supported. Proton conductive inorganic material. 2. The proton according to claim 1, wherein at least one of the oxide particles and the oxide support contains an element Z composed of Y, Sc, La, Sm, Gd, Mg, Ca, Sr, or Ba. Conductive inorganic material. Oxide particles containing at least one element X selected from the group consisting of W, Mo, Cr, B and V;
Containing at least one element M selected from the group consisting of Ti, Zr, Si and Al, and an oxide carrier on which the oxide particles are supported;
Proton conductivity characterized in that it is contained in at least one of the oxide particles and the oxide carrier and contains an element Z composed of Y, Sc, La, Sm, Gd, Mg, Ca, Sr or Ba . Inorganic material.   4. The proton conductive inorganic material according to claim 2, wherein the content of the element Z is 0.01 mol% or more and 40 mol% or less. The proton conductive inorganic material according to any one of claims 1 to 4, wherein the acidity function H _{0 of} Hammett has solid superacidity so that H ₀ <-11.93. The specific surface area is in the range of 10 m ² / g or more and 2000 m ² / g or less, and the ratio of the element X to the element Y (X / Y) is in the range of 0.0001 or more and 20 or less. The proton conductive inorganic material according to claim 1.   An electrolyte membrane comprising the proton conductive inorganic material according to claim 1 and a polymer material.   An electrode comprising the proton conductive inorganic material according to any one of claims 1 to 6, a redox catalyst, and a polymer material. A membrane electrode assembly comprising a fuel electrode, an oxidant electrode, and an electrolyte membrane disposed between the fuel electrode and the oxidant electrode,
The membrane electrode assembly, wherein at least one of the fuel electrode, the oxidant electrode, and the electrolyte membrane includes the proton conductive inorganic material according to any one of claims 1 to 6. A fuel cell comprising a fuel electrode, an oxidant electrode, and an electrolyte membrane disposed between the fuel electrode and the oxidant electrode,
7. A fuel cell, wherein at least one of the fuel electrode, the oxidant electrode, and the electrolyte membrane includes the proton conductive inorganic material according to claim 1.

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